Yep I've been through that, when you want to the car to show you that's it's playing up and it doesn't it makes you look like a crazy person. Not too sure if your car's transmission comes with check balls in the valve body but make sure to ask the specialists to make sure the sizes are all correct and in the right spot. Last time I took my valve body out I noticed one of the check balls had gone missing and had ended up in the wrong place which may have also been part of the reason why I was having issues. This check ball is supposed to sit directly next to another one and the other one was slightly bigger and was not traveling through the hole on the board while the other was. A specialist told me sometimes check balls do wear out. So it could also be part effect. It good to make sure it's all right. Transmission rebuilders and probably specialists should have all the books and specifications for them let us know how it all goes